1. Field of the Invention
The present invention relates to a solid-state imaging device and an image processing semiconductor device in which the solid-state imaging device is used.
2. Description of the Related Art
A conventional image processing apparatus has a structure as shown in FIG. 1. In FIG. 1, a solid-state imaging device 70 includes light receiving members 77 for photoelectrically converting incident light to generating signal charges according to the intensity of the light. Charge-coupled device 78 transfer the signal charges thus generated to an analog-to-digital (A/D) converter 71. The members 77 are disposed in a matrix array. A first memory 73, a second memory 74 and a third memory 75 respectively store digital image signals which are converted by the A/D converter 71. A central processing unit (CPU) 76 controls the solid-state imaging device 70, the A/D converter 71, the first, second and third memories 73, 74 and 75 through a data bus 72 according to a program stored in a memory (not shown). The solid-state imaging device 70, the A/D converter 71, the first, second and third memories 73, 74 and 75 and the CPU 76 are formed separately and assembled to form the image processing apparatus.
The conventional image processing apparatus operates as follows:
Light incident to the light receiving members 77 at a time t.sub.n (t=t.sub.n) is photoelectrically converted to generate signal charges. The signal charges thus generated are transferred to the charge-coupled devices 78 and then transferred to the A/D converter 71 by the devices 78, in which the analog signal charges are converted to digital signals, in order to obtain the digital image data D.sub.n. The image data Dn thus obtained are stored in the first memory 73 via the data bus 72 and under the control of the CPU 76.
Similar to the above, light incident to the light receiving members 77 at a time t.sub.n+1 (t=t.sub.n+1), which is a predetermined period late from the time t.sub.n, is photoelectrically converted to generate digital image data D.sub.n+1. The digital image data D.sub.n+1 are stored in the second memory 74 through the data bus 72.
Next, a finite difference operation is performed using the digital signal data D.sub.n and D.sub.n+1 stored in the first and second memories 73 and 74 respectively and as a result, image data (D.sub.n+1 -D.sub.n) thus obtained are stored in the third memory 75. Thus, data about a finite difference between two different times or a differential at a time can be obtained.
With the conventional image processing apparatus, the analog image signals obtained in the solid-state imaging device 70 are converted to digital signals and then, stored in the first and second memories 73 and 74, so that very large capacity memories are required when the resolution of the device 70 is high. For example, in case that the picture cells of the device 70 are 640.times.400 and the resolution of the A/D converter 71 is 8-bit, very large-capacity memories as many as 6144-kilobit are required.
In addition, very large burdens are acted on the A/D converter 71, the CPU 76 and the data bus 72 during operation. For example, in case that the finite difference data or differential data are operated at a frequency of 30 times in one second, 256,000 times analog-to-digital conversions and finite difference operations in one second are required, respectively. In one second, 1,280,000 or more data transfers are also required.
Therefore, the conventional image processing apparatus is difficult to be downsized and high in fabrication cost. As a result, the application field of the apparatus is very narrow.